Modern wireless communication networks often are organized in a cell structure. In LTE (3GPPP Long-Term Evolution), cells may be organized in so called cooperation areas. Cooperation areas (CAs) may be defined by one or more base stations (eNodeBs, eNBs) each serving one or more cells. Within a CA, (joint) precoding coordinated multipoint (JP-CoMP) transmission may be applied for reducing interferences within the CA.
For JP-CoMP, cooperation may be performed over different sites to achieve significant performance gains. For the precoding, all involved eNBs require the channel state information (CSI) as well as the user data for all cooperating users.
From an implementation point of view one main challenge for JP-CoMP is the distribution of huge amounts of user data over the backhaul with ultra short delay. For control information, one can setup a high priority connection providing a high probability to be available at all cooperating eNBs in time. For user data, prioritization is typically not possible or somehow meaning less due to the large amount of data. In that case, there is a certain probability that control information might be available at all eNBs of a so called cooperation area, while the according user data are still blocked somewhere in the backbone network.
One option is to provide over provisioning of the backhaul network to guarantee always that all cooperating eNBs will have all user data available within shortest time and low delay. Sufficient over provisioning in larger areas of the networks is certainly quite costly. Delaying the time instance for which eNBs wait before they start joint transmission will increase the probability that all eNBs have all user data available, even in case of only moderate over provisioning. At the same time larger delay lead to larger feedback outdating for the channel state information (CSI) degrading the performance of joint transmission significantly.
There may be a need for an improved and flexible system and method being adapted to allow a precoding coordinated multipoint transmission (like JP-COMP) and provide a fallback mode during overload of a backbone.